We have been studying the effect of deforestation on the biodiversity of tropical forest trees in Costa Rica. In this proposal we want to examine the presence of potential insecticides that would interfere with one of the vital processes of insects namely sclerotization of exoskeleton. Worldwide, insects transmit a wide variety diseases to humans as well as animals and destroy lot of agricultural products. Problems associated with synthetic insecticides in the past forced scientists to search for naturally occurring and biodegradable insecticides that would cause less damage to the environment. Since sclerotization of exoskeleton is essential for the survival of most if not all insects, it forms a nice target for the development of new insecticides. This aspect has not been explored in the past. Hence we will focus on the effect of various extracts from vascular plants (including the Leguminosae family and the Meliaceae family), bryophytes, insects and mollusks on the sclerotization of insect cuticle using three test organisms viz., Manduca sexta, sarcophaga bullata and Drosophila melanogaster. The extracts will be tested both on the isolated enzyme systems such as phenoloxidase, quinone isomerase, quinone methide isomerase, N-acyldopamine desaturase (which consists of the above three enzymes) and dopachrome isomerase and on the whole cuticle as well as whole animals. Potential inhibitors will be developed for commercial use. Simple compounds can be easily synthesized and used as commercial insecticides. However, compounds with complex structures will be isolated from plant or animal extracts for commercial use. The project will be implemented in collaboration with scientists from Biodiversity prospecting division of INBio (Instituto Nacional de Biodiversidad) in Costa Rica.